1. Field of the Invention
The present invention relates to a method of displaying an object on a monitor in color corresponding to the natural color of the object and to a digital image analysis method for automatically identifying an object in a background, characterizing the object by color by determining at least one interior point of the object, and displaying the object on a monitor in color corresponding to the natural color of the object.
2. Description Of The Related Art
The ability to access interior points of a region when its contour is given is a classic problem in image processing. Previous solutions to this problem have been described by L. W. Chang and K. L. Leu in an article entitled "A Fast Algorithm for the Restoration of Images Based on Chain Codes Description and Its Applications", Computer Vision, Graphics, and Image Processing 50, 296-307 (1990). One algorithm described, connectivity filling, requires that every pixel in the image be interrogated. Since the number of pixels within an object is greater than the number of pixels which comprise the perimeter of the object, such a technique is relatively slow. Another method described is parity checking, which is based on the fact that intersection of a straight line with the contour regions of an object delineates an even number of points on the perimeter of the object. Designation of the interior points is determined by an arbitrary filing rule where all points between each odd point and the next even point on the contour in each line of the image are designated as interior points. Such a parity checking algorithm will not work with objects of complex shape.
In the same article cited above, Chang and Leu propose an enhanced parity checking algorithm which relies on characterizing the perimeter points, created by the intersecting line segment, into one of four categories based on direction code values. Characterizing the points leads to the creation of a new buffer of perimeter points wherein some points have been duplicated and others eliminated. By applying the parity checking algorithm to the newly created buffer, interior points of objects with complex shapes may be identified. However, the enhanced algorithm presented by Chang and Leu is an indirect method to solving the problem of interior points determination requiring an excessive number of steps.
Japanese Patent Publication No. 62-60069 to Hitachi Electronic Engineering Co. Ltd., published Dec. 14, 1987, discloses a colony screening device which distinguishes colonies based on color by using interior point information. Colonies are identified by pattern recognition using a predetermined threshold, and a small number of points in the center of a colony are arbitrarily selected. U.S. Pat. No. 4,453,266 to Bacus discloses a method for identifying an object in a background. This is done by measuring the optical density of a cell using the sum of the gray level values within the closed boundaries of the cell.
None of the references discussed above discloses a digital image analysis method for displaying an object in color corresponding to the natural color of the object. Moreover, none of the references discussed above discloses a digital image analysis method for identifying and characterizing, by color, a valid object having at least one predetermined attribute value in a background by determining the interior points of an object and then displaying the object on a monitor in a color corresponding to the natural color of the object.